Insulating Sleeves for Large Generator Sets

1. Core Definition of Insulating Sleeves

Insulating sleeves are key insulating components specifically designed for generators in large-scale thermal and hydroelectric power plants. They are widely compatible with mainstream turbogenerator models such as QFSN-600-2-22, QFSN2-660-2, and QFSN-200-2. Manufactured using high-strength insulating base materials like epoxy phenolic glass cloth through lamination and one-piece molding processes, they combine excellent insulating performance with structural stability. Their core function is to provide insulation isolation and mechanical positioning for conductive components under the complex operating conditions of generators—characterized by high voltage, strong electromagnetic fields, and significant temperature fluctuations. This prevents risks such as current leakage and component short circuits, serving as an "insulation barrier" to ensure the safe operation of the generator's stator, excitation system, and oil circuit system.

2. In-depth Analysis of Core Functions

1. Dual Protection: Efficient Insulation and Precise Fixation

They not only provide insulation isolation for current-carrying conductors (e.g., stator winding leads, excitation circuit wires) when passing through metal components like frames and end covers, but also boast an insulation resistance value typically ≥10¹¹Ω and power-frequency voltage withstand capacity ≥30kV/1min—far exceeding the standards for conventional insulating components. Meanwhile, through precision dimensional design (tolerance controlled within ±0.05mm), they achieve precise positioning and fixation of conductors, resisting radial/axial vibrations (vibration frequency 50-100Hz) caused by electromagnetic forces during generator operation, and preventing insulation wear or poor contact due to conductor displacement.

2. All-condition Short Circuit Protection

Aiming at the potential conduction risk between internal conductors of the generator and grounded metal components (e.g., frame, end cover, bearing housing), insulating sleeves block the conductive path between conductors and external structures through "base material insulation + surface anti-creepage treatment" (surface creepage distance ≥25mm/kV). Even in harsh environments with 95% humidity and oil contamination, they still maintain stable insulation performance, effectively preventing major faults such as phase-to-phase short circuits and ground short circuits caused by insulation failure, and reducing the probability of unplanned unit shutdowns.

3. Harsh Environment Resistance and Structural Protection

Leveraging the temperature resistance of epoxy phenolic glass cloth (long-term operating temperature ≤155℃, short-term temperature resistance ≤200℃), they can withstand local high temperatures (e.g., 120-140℃ near stator windings) during generator operation. They also exhibit excellent oil resistance and chemical corrosion resistance, capable of withstanding erosion from lubricating oil and cooling oil inside the generator, avoiding substrate swelling or aging. Additionally, the one-piece molded structure has no seams, which can block dust and moisture from entering the insulation interior, extending the component service life.

3. Supplementary Performance Advantages

• Anti-aging Stability: Passed the GB/T 11026.1 aging resistance test. After 1000 hours of aging in a 155℃ humid heat environment, the insulation resistance attenuation rate is ≤10%, with no cracking or discoloration.

• Structural Adaptability: Supports customization of different inner diameters (Φ10-Φ50mm), lengths (50-300mm), and flange structures to adapt to installation spaces in different parts of the generator (e.g., narrow end cover areas, dense oil pipe areas).

• Safety Redundancy Design: Some key models adopt a "double-layer insulation + metal shielding layer" structure. Even if the outer insulation is accidentally damaged, the inner layer can still maintain basic insulation performance, providing safety redundancy for unit operation.

• Installation Compatibility: Sealing grooves are reserved on the surface, which can be matched with nitrile rubber sealing rings to achieve waterproof and oil-proof sealing. It is compatible with the existing assembly process of the generator, requiring no modification to installation interfaces.

4. Typical Application Scenarios and Values

1. Stator Winding Lead-out Terminals

The stator winding lead-out terminal is a key node for generator power output, with a voltage level as high as 10-20kV. Direct contact with the frame may cause corona discharge or insulation breakdown. As the core insulation component of the outlet porcelain sleeve, the insulating sleeve isolates the lead-out terminal from the frame's metal structure, while fixing the position of the lead wire to prevent wire wear caused by vibration against the porcelain sleeve. Its anti-creepage design can suppress surface discharge under high voltage, ensuring stable power output and reducing unit shutdown losses caused by lead-out terminal faults (single shutdown loss can reach hundreds of thousands of yuan).

2. Exciter-end End Cover Bearing Area

The exciter-end bearing is a core component for rotor support of the generator. If shaft current is conducted to the end cover through the bearing, it will cause electrical pitting on the bearing raceway and carbonization of lubricating grease, shortening the bearing life by more than 50%. Insulating sleeves adopt a double-insulation structure of "bearing inner ring insulation + end cover sealing insulation" here. On one hand, they block the conduction path of shaft current to the end cover; on the other hand, they isolate the bearing area from external oil contamination and moisture, maintaining a clean lubrication environment for the bearing. Meanwhile, through precise radial positioning, they ensure the coaxiality of the bearing and rotor, reducing operating noise and vibration.

3. High-pressure Oil Pipes and Jacking Oil Wedge Areas

The generator's high-pressure oil pipes (working pressure 10-30MPa) and jacking oil wedges are responsible for rotor support and lubrication. If the hydraulic oil in the oil pipes is mixed with metal impurities, it may have weak conductivity. Traditional metal sleeves easily form a conductive circuit between the oil pipe and the machine body, causing shaft current or electrostatic accumulation. Insulating sleeves isolate the electrical connection between the oil pipe and the machine body, not only preventing shaft current from being conducted to the oil system through the oil pipe and avoiding oil deterioration, but also blocking the electrostatic discharge path, eliminating the fire hazard of the oil system caused by electrostatic sparks, and adapting to the high-temperature and high-pressure working conditions of the oil system (oil temperature 60-80℃).

4. Supplementary Application Scenario: Excitation Winding Terminals

The excitation winding terminals need to transmit excitation current (hundreds to thousands of amperes). If they conduct with the stator core or frame, it will cause short circuits in the excitation circuit and magnetic field disorder, affecting the generator's voltage regulation accuracy. Insulating sleeves fix the terminal blocks here and isolate the conductive components from the grounded structure. Their high-temperature resistance can withstand the 120-140℃ high temperature near the excitation windings, ensuring the excitation system's precise control of the magnetic field and avoiding power grid frequency abnormalities caused by voltage fluctuations.

5. Selection and Cooperation Suggestions

If you are facing the following problems:

• Difficulty in matching insulating sleeves to specific generator models (e.g., QFSN2-660-2), with incorrect dimensions leading to installation jams;

• Rapid aging of sleeves under high-temperature working conditions, requiring frequent replacement which increases maintenance costs and downtime;

• Poor sealing of sleeves in the oil system, resulting in oil leakage and current leakage that threaten equipment safety;

Contact us now and provide your generator model and application location requirements to obtain an exclusive insulating sleeve technical solution and quotation, and let professional insulating components provide a reliable guarantee for the safe operation of your generator!